This programme presents four top UK scientists in who are playing an international role in the battle against the Swine Flu pandemic threat. Contributors include Dr. Othmar Engelhardt, a scientist at the National Institute for Biological Standards and Control (and HPA affiliated lab) who helped crack the genetic code of the current virus and develop a Swine Flu vaccine. Dr. Tarit Mukhopadhyay is a bio-chemical engineer at UCL advising the government on the most efficient methods for producing vast amounts of vaccine as quickly as possible. Professor Wendy Barclay of Imperial College, London is an influenza specialist who is on constant lookout for Swine Flu virus mutations, and Professor Neil Ferguson at the Medical Research Council is one of the world's top advisors and biological modellers who predicts the potential impact of the pandemic.Our contributors answer a series of questions posed by our contributing science teachers, including Why are young people at greater risk?